The dual-action ball valves are customarily employed as master valves in high pressure systems involving oil/gas separation facilities, hot oil systems, pumping stations, well heads, metering facilities, emergency shut-down systems, and the like.
It has been found that the prior art dual-action ball valves experienced excessive bearing loads on the stem guide and spiral groove when rotating the valve to the open and closed positions, and also on the cam surface on the lower end of the stem and cooperating roller pins, wherein the bearing surfaces are minimal in both areas. These weaknesses are responsible for most field problems and customer complaints.
To overcome the excessive bearing loads encountered in prior dual-action rotary valves, the dual-action rotary valve of the present invention has been devised to increase the bearing surfaces on the various components of the valve, wherein a sleeve having a pair of spiral slots is fixedly secured to the valve bonnet and the valve stem is provided with a pair of guide pins extending into the slots. A ball insert is mounted on the top of the ball valve and is provided with a bearing surface cooperating with a sloping cam surface on the lower end of the valve stem. The upper surface of the ball insert is provided with a pair of upwardly extending arcuate members engaging the lower end of the valve bonnet bushing, to thereby provide a trunnion to facilitate tilting the ball valve relative to the valve seat. The lower end of the valve stem is also provided with an arcuate concave portion which is adapted to receive a correspondingly configured convex portion on the ball insert to enhance the holding of the ball valve in the closed position.